Question

What are the solutions of the quadratic equation? x2 – 9x + 20 = 0 ?

Answer 1

for factorizing the standard quadratic equation,\( ax^2+bx+c=0\), we need 2 numbers whose sum is 'b' and product = ac
for your Question,
can you find 2 numbers whose sum = -9 and product = 20 ?

Answer 2

-5 and -4 ?

Answer 3

correct!
so split up
-9x as -5x-4x
x^2-5x-4x+20 =0
can you factor out 'x' from 1st two terms ?

Answer 4

I don't know how

Answer 5

would I do 5+(-1x)=0 ?

Answer 6

x^2-5x-4x+20 =0
x (x-5) -4 (x-5) = 0
see what i did ?

Answer 7

yes

Answer 8

now factor out x-5 from that ?
what do u get ?

Answer 9

x-4=0 ?

Answer 10

x (x-5) -4 (x-5) = 0
(x-5)(x-4) =0
so,
x-5 = 0
x-4 = 0
x=5, 4

Answer 11

Thank you ( :

Answer 12

welcome ^_^